Adjustable plunger switch



Filed Jan. 23, 1962 cwar/er ,4. Waaocaa United States Patent Office 3,190,982 Patented June 22, 1965 3,130,982 ADJUSTABLE PLUNGER SWITCH Charles A. Woodcock, Springfield, IlL, assignor to Stewart-Warner *Corporation, Chicago, Ill., a corporation of Virginia Filed Jan. 23, 1962, Ser. No. 168,195 2 Claims. (Cl. ZOO-61.81)

\ This invention relates to a plunger-type switch, and in particular, to an improved mounting therefor operable to adjust automatically the opening and closing setting of the switch upon initial use thereof.

A plunger-type switch generally includes electrical contacts that are opened and closed by axial movement of a plunger within the switch casing. The casing is secured to one structure to support the switch; while a second structure moving relative to the supporting structure moves the plunger to actuate the switch. The position of the switch relative to the advance of the actuating structure determines the opening and closing setting of the switch.

An example of such a. switch arrangement is that commonly used with a door structure, where the switch plunger is actuated by the door during opening and closing thereof. Because the switch is used in many sizes and types of door structures, and in fact because even identical door structures have slightly different tolerances, the position of each switch relative to the advance of its actuating door generally must be individually adjusted. Not only is existing adjustment structure complicated and expensive to fabricate, but the adjustment time in man hours is also costly.

Accordingly, an object of this invention is to provide a plunger switch with an improved mounting operable to adjust the effective opening or closing setting of the switch automatically upon initial use thereof.

Another object of this invention is to provide an improved plunger switch mounting which can be economically formed of conventional stock by simple fabrication thereto.

These and other objects will be more fully appreciated after a complete disclosure of the subject invention given in the following specification, the drawing forming a part thereof, wherein:

FIG. 1 is a plan view of a plunger switch in a mounted position and incorporating a specific embodiment of the subject invention;

FIG. 2 is a longitudinal section view of the plunger switch shown in FIG. 1; and

FIG. 3 is a section view as seen generally from lines 3-3 of FIG. 2.

Referring now to FIG. 1 of the drawing, a plunger switch includes a casing 12, a pair of terminals 14, a mounting tube 16 projecting from the casing 12 in the opposite direction of terminals 14, and a plunger 13 slidable within the tube 16 and casing 12. The switch 10 is secured in its operative arrangement to a frame member 29 which, for example, can be a door post of an automotive vehicle. Member 22, which can be the door of the vehicle, is movable toward and away from frame 20 to abut plunger 18 of the switch 10 for actuation thereof.

Referring now to FIG. 2, the casing 12 and tube 16 of the switch 10 are continuous cylinders interconnected as by crimping at 24. The casing 12 receives insulating members 26, formed for instance from a plastic material, which hold separate the electrical conductive members 28 forming the inner ends of terminals 14, shown in FIG. 1. The conducting members 28 have spaced stationary contacts 30 which are separated from one another electrically.

An annular conducting member 32 is received within recess 34 at the inner end of plunger 18 and defines the moving contact of the switch. Moving contact 32 engages contacts 30 in the switch closed position to complete a circuit across terminals 14 and is spaced from the contacts 30 to break the circuit in the switch open position. Plunger 18 is hollowed out at bore 36 which houses therein compression spring 38 guided on nail 40 supported by and insulated electrically from the casing 12 by means (not shown) common in the art. The compression spring 38 urges the plunger 18 and moving contact 32 against the stationary contacts 30 to maintain the switch 10 in the closed position.

Referring now to the improved mounting for switch 10, it will be noted that tube 16 is of continuous construction around its entire periphery. The tube 16 thus can be of commercially available tubular construction having uniform wall thickness and of cylindrical shape. A bushing nut 42 is received in threaded opening 43 in the frame member 20 and presents a bore 44 of uniform cross-section along its length.

The interior diameter of bore 44 and exterior diameter of tube 16 are chosen appropriately to provide a generally snug but freely movable fit. The intermediate portion of the tube 16 spaced from end portion 46 is flattened out or swaged, as shown in the drawing, by simple impact or pressure means. The swaging thus causes the previously circular cross-section tube 16 to become out of round and present opposing portions 48 of greater dimension and opposing portions 50 of lesser dimension than the unswaged tube. The high sides 48 of the swaged tube thus cannot clear the periphery of bore 44, so that upon insertion of end portion 46 therein tube 16 and nut 42 become frictionally interlocked.

When mounting the plunger switch 10 operatively, the nut 42 is threaded into opening 43 in the frame 20. The end portion 46 of tube 16 is inserted into the bore 44 and the entire casing 12 and tube 16 biased against the frictional resistance of the swaged portion 48 and nut 42 until the casing abuts the rearward side of the nut. Thus the plunger 18 is projecting from the frame 20 toward the actuating member 22 by its maximum amount.

Upon actuation of member 22 toward the frame 20, the plunger 18 will be biased against spring 38 to separate the moving contact 32 from contacts 30 and actuate the switch. However, the switch initially may be positioned improperly, so that the advancing member 22 could depress plunger 18 completely and abut the end 52 of the tube 16. The assembly is designed so that tube 16 within nut 42 creates sufi'icient friction force to oppose without movement thereof, the force of spring 38 but which is insuflicient to oppose the force of advancing member 22. Upon member 22 abutting tube end 52 the entire switch It) will move relative to nut 42 to the position corresponding to the furthest advance of member 22 toward the frame 20. Thus, the frictional fit between the swaged tube 16 and nut 42 will automatically adjust the proper opening or closing setting of the switch as required.

While the embodiment shown has separate tube 16 secured to the casing 12, it would be entirely possible to swage the casing 12 and thus completely eliminate the tube. The important feature of the improved mounting is that the swaged member is a simple structure having a continuous wall without axial splits or separations along its length. The member which fits within the receiving bore before swaging is swaged to create a greater crossdimension than the bore for establishing friction fit therebetween. The swaged member with its continuous wall structure is of sturdy construction capable of maintaining tight friction fit even after repeated use of the switch.

While a single embodiment has been shown it will be obvious to those skilled in the art that various modifications may be made therein without departing from the inventive concept. It is, therefore, desired that the in- Vention not be limited by the embodiment shown but by the appended claims.

What is claimed is:

1. A plunger switch adapted for frictional retention in and axial adjustment through a cylindrical bore through a suitable support member, said switch comprising a casing which includes a tube having a free open end, a plunger guided for axial movement through said tube with one end of the plunger extending into said casing, spring means normally resiliently projecting said plunger axially toward and through the free end of said tube to a predetermined operational position, switch contacts carried by said plunger and casing for actuation responsive to axial movement of the plunger, said plunger being movable inwardly completely through said free end, whereby axial pressure on the plunger in excess of that required to thus move it inwardly completely through said'free end may be exerted on said free end of the tube to adjust the axial position of said tube within the said bore, said tube having a medial first portion spaced axially from said free open end and normally of greater external diameter in one diametral plane than said through bore to provide a frictional but axially adjustable fit of the tube within the bore, and of smaller internal diameter than said bore in a diametral plane transverse to said one diametral plane for guiding engagement with said plunger, a second por- 4 tion extending from said free open end to said first portion being of cylindrical configuration and proportioned for free axial reception and movement in said bore to function as a pilot for guiding said first portion into the bore during assembly of said plunger switch.

2. A plunger switch as defined in claim 1 in which said tube includes a third portion remote from said free end, said third portion being of the same uniform diameter as said second portion and internally dimentioned for free axial reception of said plunger, said third portion merging with said second portion to guide the plunger into said second portion during assembly of the switch.

References Cited by the Examine:

UNITED STATES PATENTS 2,382,996 8/45 Jacobi 200166 2,418,905 4/47 Sage 200-61.81 2,671,151 3/54 Hollins 200166 2,801,309 7/57 Higbie et al 200-159 2,921,155 1/60 Basso 200-l59 2,972,033 2/61 Woodcock 200--61.81 3,115,559 12/63 Cass et al. ZOO-61.89

ROBERT K. SCI-IAEFER, Acting Primary Examiner.

BERNARD A. GILHEANY, Examiner. 

1. A PLUNGER SWITCH ADAPTED FOR FRICTONAL RETENTION IN AND AXIAL ADJUSTMENT THROUGH A CYLINDRICAL BORE THROUGH A SUITABLE SUPPORT MEMBER, SAID SWITCH COMPRISING A CASING WHICH INCLUDES A TUBE HAVING A FREE OPEN END, A PLUNGER GUIDED FOR AXIAL MOVEMENT THROUGH SAID TUBE WITH ONE END OF THE PLUNGER EXTENDING INTO SAID CASING, SPRING MEANS NORMALLY RESILIENTLY PROJECTION SAID PLUNGER AXIALLY TOWARD AND THROUGH THE FREE END OF SAID TUBE TO A PREDETERMINED OPERATIONAL POSITION, SWITCH CONTACTS CARRIED BY SAID PLUNGER AND CASING FOR ACTUATION RESPONSIVE TO AXIAL MOVEMENT OF THE PLUNGER, SAID PLUNGER BEING MOVABLE INWARDLY COMPLETELY THROUGH SAID FREE END, WHEREBY AXIAL PRESSURE ON THE PLUNGER IN EXCESS OF THAT REQUIRED TO THUS MOVE IT INWARDLY COMPLETELY THROUGH SAID FREE END MAY BE EXERTED ON SAID FREE END OF THE TUBE TO ADJUST THE AXIAL POSITION OF SAID TUBE WITHIN THE SAID BORE, SAID TUBE HAVING A MEDIAL FIRST PORTION SPACED AXIALLY FROM SAID FREE OPEN END AND NORMALLY OF GREATER EXTERNAL DIAMETER IN ONE DIAMETRAL PLANE THAN SAID THROUGH BORE TO PROVIDE A FRICTIONAL BUT AXIALLY ADJUSTABLE FIT OF THE TUBE WITHIN THE BORE, AND OF SMALLER INTERNAL DIAMETER THAN SAID BORE IN A DIAMETRAL PLANE TRANSVERSE TO SAID ONE DIAMETRAL PLANE FOR GUIDING ENGAGEMENT WITH SAID PLUNGER, A SECOND PORTION EXTENDING FROM SAID FREE OPEN END TO SAID FIRST PORTION BEING OF CYLINDRICAL CONFIGURATION AND PROPORTIONAL FOR FREE AXIAL RECEPTION AND MOVEMENT IN SAID BORE TO FUNCTION AS A PILOT FOR GUIDING SAID FIRST PORTION INTO THE BORE DURING ASSEMBLY OF SAID PLUNGER SWITCH. 